Why are enzymes important?

Enzymes are proteins that control the speed of chemical reactions in your body. Without enzymes, these reactions would take place too slowly to keep you alive. Some enzymes, like the ones in your gut, break down large molecules into smaller ones. Others, like the enzymes that make DNA, use small molecules to build up large complex ones. Enzymes also help cells to communicate with each other, keeping cell growth, life and death under control.